Gum base compositions generally include, among other things, components known in the art as elastomers. Elastomers commonly used in gum bases include polyvinyl acetate and hard elastomers such as styrene-butadiene rubber. Vinyl laurate/vinyl acetate copolymer has also been suggested for use in gum bases, however, its use has been restricted to gum bases containing polyvinyl acetate, particularly high molecular weight polyvinyl acetate.
Gum bases also typically contain a softener component. The type of softener added to a gum base composition is often dependent on the type of elastomer in the base. In the past, certain elastomers have been found to be compatible with only a limited number of softeners. For example, gum bases containing polyvinyl acetate have been limited primarily to containing glycerol triacetate as a softener. Glycerol triacetate, however, has a tendency to volatize out of the base during processing and may cause a bitter taste in the final gum product.
The processing of gum bases may also be dependent on the type of ingredients in the base. Generally, gum bases are processed with the use of heat. Some bases containing polyvinyl acetate may require cooling in order to achieve sufficient miscibility of the gum base components. In contrast, some other elastomers require increased temperatures during processing. Processing gum bases with excessive heat, however, has been found to damage the elastomer in the base. For example, heating the elastomer to too high temperatures, i.e. above 200.degree. C, may cause depolymerization of the elastomer. Elastomer depolymerization generally results in a low molecular weight polymer that can reduce stiffness of the final gum product.